Impact of stress exponent on steady state creep in a rotating composite disc

Abstract

The effect of the stress exponent on the steady state creep in a rotating disc made of isotropic aluminium–silicon carbide particulate (Al–SiCp) composite has been investigated. The creep behaviour of the composite has been described by threshold-stress-based creep law, with different values of true stress exponent n as 3, 5, and 8. The creep parameters appearing in the law have been extracted from the experimental creep data available for Al–SiCp under uniaxial loading. It is observed that the steady state creep in Al–SiCp under uniaxial loading could be explained in a better way by assuming n = 5 rather than n = 3 or 8. The trend of stresses and strain rates in the disc does not change on varying the value of the stress exponent. The values of stresses and strain rates in the disc are, however, significantly affected by varying the stress exponent. The steady state creep rates in the disc increase by about two orders of magnitude on increasing the stress exponent from 3 to 8. The stresses as well as strain rates in the disc corresponding to n = 5 lie between the corresponding values estimated using n = 3 and n = 8.